Ending months of protracted negotiations, the Department of Corrections agreed with the U.S. Department of Labor to provide back pay or compensatory time to 710 correctional officers at the state's largest and oldest prison, Union Correctional in Raiford.

Acting on complaints by two prison guards and the Teamsters Union, the Labor Department's Wage & Hour Division began an investigation at Union in Raiford in 2011. The findings cited the state's "failure to pay employees at least the applicable minimum wage for all hours worked," and failure to pay overtime.

The underpayments, which occurred from 2009 to 2011, totaled $603,237.45.

The Labor Department found that officers were not paid while they waited in line to be patted down and pass through metal detectors, receive tear gas canisters and walk to assigned posts at far-flung inmate dormitories, a process that officers said can take 25 minutes.

The state took the position that under federal law, workers' "principal activity" did not start until they arrived at their posts, not when they received cans of chemical agents.

Current employees will receive time off starting in July, and some will get two months off. Former employees will get checks, some for more than $3,000, for wage and hour law violations.

As the confidential investigation dragged on, it remained a mystery to rank-and-file employees such as Karen Bridwell, 56, of Lake Butler, who will receive one of the largest checks, for nearly $3,100.

"I'm glad to get it," said Bridwell, who retired as a correctional officer more than a year ago. "I was surprised. I didn't even know it was going on."

Bridwell earned $37,597 at the time of her retirement, after a 27-year career in the prison system.

She said it was unfair for the state not to have paid her from the moment her hands touched a tear gas canister.

"The second you put your hands on state property, that's when the clock needs to run," Bridwell said.

Corrections Secretary Mike Crews said the agency has changed its policies so that officers are given tear gas canisters when they arrive at their posts.

"We had to restructure that a little bit," Crews said.

In all, the state must pay former employees more than $234,000 and grant more than 23,000 hours of time off to current workers, the equivalent of 575 40-hour work weeks. The concessions come at a time when the agency is struggling to fill shifts at its most dangerous prisons, including Union, where many death-row inmates are houses.

State workers won't get their checks or time off until the new fiscal year begins July 1. The agency doesn't have the money in the current year's budget.

Crews, who took over the nation's third-largest prison system last December, testified before a Senate committee in March that the prison system was $95 million in the red.

A Teamsters Union official in Washington, Michael Filler, said he was pleased with the outcome of the case.

"We need a commitment to transform and reform the way the department operates," Filler said, "and we want to be partners in that enterprise."

Legislators who oversee the prison system and approve its budget also were unaware of the federal investigation.

Sen. Rob Bradley, R-Fleming Island, who chairs a Senate committee on criminal justice spending, said the short-changing of workers underscores the need for the prison system to switch from using paper time sheets to an electronic system of keeping employees' attendance.

Prison employees and lawmakers weren't the only ones in the dark about the case. The Department of Corrections itself filed a Freedom of Information Act request with the Labor Department, seeking a copy of the investigation of which it was a target. The feds refused, saying that disclosure "could interfere with a law enforcement proceeding."

Steve Bousquet can be reached at bousquet@tampabay.com or (850) 224-7263.